DP Chemistry (last assessment 2024)

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Question 21M.2.sl.TZ1.d(i)

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Date May 2021 Marks available [Maximum mark: 3] Reference code 21M.2.sl.TZ1.d(i)
Level sl Paper 2 Time zone TZ1
Command term Determine Question number d(i) Adapted from N/A
d(i).
[Maximum mark: 3]
21M.2.sl.TZ1.d(i)

Hydrogen peroxide can react with methane and oxygen to form methanol. This reaction can occur below 50°C if a gold nanoparticle catalyst is used.

Consider the first stage of the reaction.

CH4 (g) + H2O (g) ⇌ CO (g) + 3H2 (g)

Determine the enthalpy change, ΔH, in kJ. Use section 11 of the data booklet.

Bond enthalpy of CO = 1077 kJ mol−1.

[3]

Markscheme

Σbonds broken = 4 × 414 «kJ» + 2 × 463 «kJ» / 2582 «kJ» ✔

Σbonds formed = 1077 «kJ» + 3 × 436 «kJ» / 2385 «kJ» ✔

ΔH «= Σbonds broken − Σbonds formed =( 2582 kJ − 2385 kJ)» = «+»197«kJ» ✔


Award [3] for final correct answer.
Award [2 Max] for final answer of −197 «kJ»

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